Exercise Key for Staving Off Metabolic Syndrome

Benefits of physical activity seen across BMI levels

Regardless of weight, inactivity may be a precursor to metabolic syndrome, according to a new study.

Independent of body mass index (BMI), greater cardiorespiratory fitness in men was linked to a smaller waist circumference (-0.57 in [-1.45 cm], 95% CI -0.61 to -0.53 in [-1.55 to -1.35 cm], P<0.001) and less inflammation (high sensitivity C-reactive protein [hsCRP] -0.22 mg/L, -0.255 to -0.185 mg/L, P<0.001), reported Anne-Sophie Wedell-Neergaard, MD, of the University of Copenhagen in Denmark, and colleagues.

As shown in the study, published online in PLOS One, this inverse relationship with increased fitness was also apparent in women for both abdominal adiposity (-0.45 in [-1.15 cm], 95% CI -0.49 to -0.39 in [-1.25 to -1.0 cm], P<0.001) and inflammation (hsCRP -0.26 mg/L, -0.3 to -0.22 mg/L, P<0.001).

In both sexes, more abdominal fat -- marked by a 0.39 inch (1 cm) increase in waist circumference -- was also tied to more inflammation, independent of BMI, as follows:

Men: hsCRP +0.03 mg/L, 95% CI 0.02-0.037 mg/L, P<0.001

Women: hsCRP +0.025 mg/L, 0.017-0.034 mg/L, P<0.001

"The use of BMI alone in predicting metabolic health is controversial," the researchers wrote, adding that around 30% of people with obesity are considered to be "metabolically healthy," marked by a combination of high insulin sensitivity, low abdominal fat, and low inflammation.

In order to determine whether markers of metabolic syndrome were present at all BMI levels, the research group assessed 10,976 individuals (n=4,638 men; n=6,338 women) from the Danish National Health Examination Survey.

The cross-sectional study began with a self-reported health survey, along with a clinical examination to determine BMI, waist circumference, and inflammation levels. Exclusion criteria included a history of any heart-related disease, moderate to severe hypertension, chest pain or pressure, pregnancy, and use of heart, hypertension, or pulmonary treatments.

Higher cardiorespiratory fitness -- defined as +5 mL min-1 kg-1 -- was determined based on a maximal cycle ergometer test. Non-fasting venous blood samples were collected to determine the extent of low-grade inflammation, a predictor of disease, based on hsCRP levels.

At baseline, more than half of the men were either overweight or obese (BMI 25.2, 23.3-27.4), while the women were generally normal weight (23.4, 21.5-26.1). Both men and women tended to have normal levels of inflammation (0.9 mg/L, 0.3-1.8; 0.9 mg/L, 0.3-2.0, respectively), while median cardiorespiratory fitness levels were 35.9 mL min-1 kg-1 for men and 31.5 mL min-1 kg-1 for women.

Possible limitations to the study, the researchers said, include the method of measurement used to calculate the relationship between fitness and waist circumference: "It could be that, when comparing individuals of different height but the same BMI and VO2 max, the taller participants have physiologically larger waist circumferences and weigh more than their shorter counterparts. This results in the calculation of a lower fitness, since the formula for fitness is VO2 max divided by body weight." This method could have potentially led to a "false correlation," despite height being adjusted for in the analysis.

Ultimately, Wedell-Neergaard's group recommended that in order "to obtain a more accurate identification of individuals who are healthy despite obesity and individuals who are at metabolic risk despite normal weight, the data suggest that measurements of waist circumference, hsCRP, and fitness should be taken into account."

The Centre for Physical Activity Research is supported by a grant from TrygFonden and the Centre of Inflammation and Metabolism and the Danish National Research Foundation.

Wedell-Neergaard and co-authors reported having no conflicts of interest.

Accessibility Statement

At MedPage Today, we are committed to ensuring that individuals with disabilities can access all of the content offered by MedPage Today through our website and other properties. If you are having trouble accessing www.medpagetoday.com, MedPageToday's mobile apps, please email legal@ziffdavis.com for assistance. Please put "ADA Inquiry" in the subject line of your email.